54 Report of the Department of Agronomy <>k the 



the farmer who cannot spend more than about $2 per acre per year 

 for fertilizers would best spend all of this for phosphorus and limestone; 

 or if his land does not need lime spend the greater part of it for 

 phosphorus. He should also in every way practicable supply 

 liberal amounts of organic matter by the use of all available farm 

 manure, crop residues and occasional green-manure crops, making 

 use to a large extent of legume crops, which have the ability of 

 securing nitrogen from the air. The statement is ventured that the 

 majority of New York State farmers have not money to spend for 

 fertilizers beyond $2.50 per acre per year for their entire land in crops. 

 But at this cost phosphorus and lime carbonate can be supplied in 

 larger quantities than they are reduced by cropping and thus the 

 soil be positively enriched in these materials. There is good evidence 

 to show that by this method the soil can be brought up to a high 

 state of fertility and good crop yields indefinitely maintained. The 

 following specific examples are illuminating: 



A practical farmer has bought run-out land in southern Illinois 

 at $15 per acre and at an annual expense of $1.75 per acre for 

 limestone and phosphorus for the last ten years has gradually 

 increased the yields to 35§ bushels of wheat per acre in 1913. Check 

 strips not so treated produced 11| bushels per acre for the same 

 year. 



Another Illinois farmer on more productive land by the expendi- 

 ture for the previous five years of $1 per acre per year for phosphorus 

 alone (his land not being in need of additional lime carbonate) 

 has increased the yield of corn from 54 bushels per acre to 70 bushels; 

 oats from 47 bushels to 70 bushels, and clover hay from 1| tons to 

 2\ tons; these yields being 5-year averages. 



At the Illinois State Experiment Station wheat has yielded 34.2 

 bushels per acre on land treated with cover crops and farm manure. 

 On land similarly treated except for the addition of phosphorus at 

 the rate of $1.90 worth per acre annually for the past four years 

 the yield at the same time has been 51.8 bushels of wheat. 



It is important to note that results brought out by field experiments 

 as to the needs of soils for phosphorus, lime carbonate and organic 

 matter, and the unprofitableness in most cases of supplying nitrogen 

 and potassium in commercial forms are in accord with the logical 

 inferences to be made from the data revealed by chemical analyses. 

 The two together form a safe foundation upon which to base a rational 

 system of soil management. 



Carriers of phosphorus. — The principal fertilizing materials that 

 can profitably be used for supplying phosphorus are the following: 



Per ct. P. Per ct. P,0 5 



Acid phosphate, containing 6- 7 ) ( 14-16 



Bonemeal, containing 9-12 J 20-27 



Basic slag phosphate, containing 7-8 j 16-18 



Natural rock, containing 12-14 J [ 28-32 



